In our pending U.S. application Ser. No. 08/851,465 filed May 5, 1997, the contents of which are incorporated herein by reference, there is disclosed a fuel powered heater used for heating fluid which fluid is subsequently used for circulation throughout a heating system and which finds particular application in boats and recreational vehicles. While the heated fluid is used to warm the environment in the vehicle or boat wherein the heater is placed, it is often the case that heated potable water is also useful for cooking, drinking, washing and the like within the recreational vehicle or boat. Heretofore, such heated potable water has generally been produced by a heater independent from the heating system used for heating the vehicle or boat and the fuel used in such independent heaters is usually propane.
It is also often desired that the fuel powered heater used for heating fluid be supplemented or replaced by an AC powered heater if there is a source of AC power available. This might be the case where the boat is docketed and AC power is available or where the recreational vehicle is in an RV park where AC power is available.
WO 99/61884 (Rixen), published Dec. 2, 1999 and entitled HEATING SYSTEM FOR POTABLE WATER AND RELATIVELY SMALL AREAS, teaches a heating system used to heat a recreational vehicle which system is also used to heat potable water. This system is an advance in an attempt to achieve potable water and space heating with an integrated system. However, Rixen teaches a supplemental heater and a heat exchanger, which supplemental heater heats a second liquid independent from the heating of the first fluid. The use of two powered heaters to heat two fluids, one for each fluid, is costly and creates additional servicing and maintenance problems. Further, Rixen's apparatus is not operated automatically. He requires manual operation of the components of his heating system which manual operation is often very inconvenient.